Liquid valve arrangement



June 8, 1965 D. s. FRANK ETAL 3,187,765

LIQUID VALVE ARRANGEMENT Filed May 28. 1962 IZZ OUTLE T FURNACE INVENTORS DAVID S. FRANK FREDERICK B. CALLANE'N United States Patent 3,187,765 LIQUTD VALVE ARRANGEMENT David S. Frank, Chicago, Frederick E. Callahan, Barrington, and Victor A. Walter, Northbrook, 111., assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio Filed May 28, 1962, Ser. No. 1%,188

3 Claims. (l.'137--253) This invention relates to valve means for directing the discharge of hot gases to means for recovering the heat value of the gases, or to a flare.

In certain industrial processes there is produced a hot gaseous effluent which at times must be conveyed directly to a flare, while at other times it is conveyed to a further processing stage. For example, the gaseous eflluent of the catalyst regenerator of an oil cracking system has a substantial amount of combustible gas, i.e., car- 'bon monoxide, and is at a temperature mually between about 900 and 1100' F. It is generally desirable to convey this gas to a furnace where the burnable portion thereof is combusted and the combustion gases from this furnace pass over heat exchange devices. In this way both the sensible heat value and the fuel value of the gases are utilized. However, there are times when, for one reason or another, it is impossible to introduce the gas into the furnace, and it must be conveyed directly to a stack or flare for discharge to the atmosphere. Because of the large amount of gas handled and its high temperature, large valve organizations are required to controllably direct the gas to the furnace or to the flare. In accordance with this invention liquid seal type valves are employed for this purpose.

It is therefore a primary object of this invention to provide a novel and improved liquid seal organization. Another object of this invention is to provide an improved valve means comprising two liquid seals which act in cooperation to direct a hot gaseous stream to a flare or to heat recovery means.

The invention is best described with reference to the drawing, which shows an elevational view of an organization embodying the instant invention. The apparatus is seen to consist of two liquid seals, designated generally It and 12, together with a third and different seal liquid container 14. The liquid seals 16 and 12 are identical, and comprise a vessel 20 which is provided with a gasoutlet 22 and a gas-inlet conduit 24 which extends vertically within vessel 24 from below a selected datum line 2-5 upwardly above the datum line and outward through the wall of the vessel 20 at 28. A sealed relationship between conduit 24 and the vessel wall exists at point 28. This is most conveniently accomplished by means of a welded joint. Conduit 24 communicates with gas-inlet line 29. Liquid seal 14) is further provided with a valvecontrolled sealing-liquid line 3% and a drain line 32. An inverted siphon leg 34 communicates with vessel 26 below datum line 26, and extends upward to the level of datum line 26 at 36, and then extends downward to a lower terminus 38. The downwardly extending leg 46 of inverted siphon 34 enters seal liquid container 42, which is provided with an overflow 44. The overflow 44 is positioned below datum line 26, and preferably below the point of communication 46 of inverted siphon 34 with vessel 24). It is further preferred that the lower open end of gas inlet conduit 24 terminate at a position between datum level 26 and point 4-6.

In accordance with this invention, a siphon breaking device Si is provided to prevent siphoning of sealing liquid rom vessel 20 by means of siphon leg 34. This siphon breaking device comprises a conduit which communicates with inverted siphon leg 34 at datum level 26, which is the 3,187,755 Patented June 8, 1965 upper extremity of the siphon leg, and with vessel 2!) at a point substantially above datum level 26.

Liquid seal 12 is identical with the aforedescribcd liquid seal it and therefore will not be described in detail. As shown in the drawing, liquid seal 19, which communicates with the stack or flare, is closed by sealing liquid 54; whereas liquid seal 12 is open to permit the flow of gases to the heat recovery furnace.

In operation, a continuous flow of water enters vessel 2d of liquid seal through valve-controlled conduit 30. The rate of water flow is maintained at a value lower than the capacity of inverted siphon leg 34. Since the pressure in the upper portion of vessel 10, external of gasinlet conduit 24, is substantially atmospheric pressure, the liquid seeks the level of datum line 26, and as liquid continues to enter vessel overflow occurs through inverted siphon leg 34. The etlluent water flows downward to liquid container 42 and thence out of container 42 through overflow means 44. The pressure within the vertical inlet conduit 24 is above atmospheric pressure, and accordingly the liquid level within the low-er portion of conduit 24 is depressed to counter-balance the net gauge pressure by which the efiluent from the catalyst regenerator, in line 29, exceeds atmospheric pressure.

Since there is no liquid in liquid seal 12, gas from line 29 flows downward through vertical gas-inlet conduit 124 and then outward through outlet 122 for processing to recover the heat value of the gas. it will be evident that the pressure existing within vessel 12d of liquid seal 12 is ubstantially the pressure in inlet line 29, and this pressure is transmitted through inverted siphon leg 13 Escape of gas through this siphon leg is prevented by means of the liquid seal provided by container 42, the liquid level in container 42 being always maintained by the constant stream or" water coming downward from siphon leg 34. Thus the water which provides a continuous change of liquid for seal iii also provides a liquid seal for the siphon leg 134.

It has been found that for satisfactory results in high temperature liquid seals it is necessary that the sealing water be changed continuously to prevent over-heating of the water or contamination of the water with solids from the catalyst regenerator. It has been found that this can be best accomplished by means of an inlet feed line 3d and a siphon leg of higher capacity than the inlet line, the siphon leg serving to retain the liquid level at the desired datum level irrespective of variations in liquid inlet flow rates. Such systems nevertheless suffer from the disadvantage that it is possible for the inverted siphon leg to act as a siphon to remove water more rapidly than water is provided, whereby the liquid evel in vessel 24? would be reduced below datum level 26.

It has been found that this can be effectively prevented by connecting a conduit such as conduit 54 between the upper portion of vessel 29 and inverted siphon leg 34 at the. upper extremity thereof, i.e., at the datum level.

When for some reason it is desired to shut down the furnace, and exhaust the efiluent gases to a flare, valvecontrolled outlet 32 of liquid seal 10 is opened, and liquidinlet conduit is closed, draining the liquid from seal 19. Thereafter, liquid-inlet conduit 139 is opened and valve controlled drain 132 is closed. The vessel 12%? then fill to the datum level determined by the upper extremity of siphon leg 134. The fiow of gas from inlet line 29 to outlet 22 is then unobstructed. It will be observed that when so conditioned to exhaust the hot gases to outlet 22, the gaseous pressure is exerted through the inverted siphon 34 also. However, overflow water from liquid seal 12 passes through inverted siphon 134 and, in cooperation with overflow 44 of container 42, maintains a seal which prevents the escape of gas through inverted siphon leg 34.

While the apparatus has been described with reference to a device for alternatively directing hot gases from a catalyst regenerator to a flare or to heat recovery means, the apparatus is applicable wherever it is desired to direct a large volume of hot, low pressure gases to one of two courses. While water is the most convenient fluid for use as the liquid sealant, it will be evident that other liquids, especially aqueous liquids, can be used. Also,-the overflow from vessel 42 can be picked up as by means of a pump and returned as inlet liquid to liquid seal 10 or liquid seal 12. Other modifications of the apparatus as specifically disclosed will be obvious to those skilled in the art.

The emobdiments of the invention in which an exelusive property or privilege is claimed are defined as follows:

1. Valve means for controlling the flow of low pres- 7 communicating with the bottom of said vessel, a liquid container having an overflow positioned below said datum level, an inverted siphon communicating with said vessel at a point below said datum level, extending upward-' 1y to said datum level and then extending downward into said liquid container to a terminus positioned below the level of said overflow, and siphon breaking means comprising a conduit communicating with said inverted siphon at said datum level and with said vessel at a point above said datum level.

2. Valve means for directing the flow of hot, lowpressure, high-temperature gases comprising a first liquid sealincluding a closed, vertically extending vessel, said vessel having a gas-outlet communicating therewith at a point above a selected datum level, a gas-inlet conduit, extending vertically within said vessel from a lower end positioned below said datum level to a point above said datum level and thence outward through a wall of said vessel in sealed relation therewith, a valve-cont rolled liquid-inlet communicating with said vessel, a valve-controlled drain communicating with the bottom of said vessel, an inverted siphon communicating with said vessel at a point below said datum level, extending upwardly to said datum level, and then downwardly to a lower end, and a conduit communicating with said inverted siphon at, said datum level and with said vessel at a point above said datum level; a second liquid seal as aforedefined, the gas inlet conduits of saidliquid seals both communicating with same gas inlet line, and a liquid container provided with overflow means positioned with said overflow means below said datum level, the lower ends of said inverted siphons being disposed within said liquid container below said overflow means.

'3, Valve means in accordance with claim 1 wherein the Walls of said gas-inlet conduit are fluid impermeable between said datum level and the point at which said gas- I inlet conduit passes outwardly through the wall of said vertically extending vessel.

References Cited bythe Examiner UNITED STATES PATENTS 2,721,065 10/55 Ingram l37253 XR ISADOR WEIL, Primary Examiner.

WILLIAM F. ODEA, Examiner. 

1. VALVE MEANS FOR CONTROLLING THE FLOW OF LOW PRESSURE, HIGH TEMPERATURE GASES COMPRISING A CLOSED, VERTICALLY EXTENDING VESSEL, A GAS-OUTLET COMMUNICATING WITH THE UPPER END THEREOF, A GAS-INLET CONDUIT EXTENDING VERTICALLY WITHIN SAID VESSEL FROM A LOWER END POSITIONED BELOW A SELECTED DATUM LEVEL TO A POINT ABOVE SAID DATUM LEVEL AND THENCE OUTWARD THROUGH A WALL OF SAID VESSEL IN SEALED RELATION THEREWITH, A VALVE-CONTROLLED LIQUID-INLET COMMUNICATING WITH SAID VESSEL, A VALVE-CONTROLLED DRAIN COMMUNICATING WITH THE BOTTOM OF SAID VESSEL, A LIQUID CONTAINER HAVING AN OVERFLOW POSITIONED BELOW SAID DATUM LEVEL, AN INVERTED SIPHON COMMUNICATING WITH SAID VESSEL AT A POINT BELOW SAID DATUM LEVEL, EXTENDING UPWARDLY TO SAID DATUM LEVEL AND THEN EXTENDING DOWNWARD INTO SAID LIQUID CONTAINER TO A TERMINUS POSITIONED BELOW THE LEVE OF SAID OVERFLOW, A SIPHON BREAKING MEANS COMPRISING A CONDUIT COMMUNICATING WITH SAID INVERTED SIPHON AT SAID DATUM LEVEL AND WITH SAID VESSEL AT A POINT ABOVE SAID DATUM LEVEL. 